Nonaqtjeotts electrolytic condenser



June 5, 1928.

E. w. ENGLE NONAQUEOUS ELECTRLYTIC CONDENSER Filed Aug. 29, 1927 Patented June 5, 1928.

UNI-TED vSTATES tamil PATENT orrics.

EDGARAW. ENGLE, 0F LAK FOREST, ILLINOIS, ASSIGNOR TO FANSTEEL PRODUCTS COMPANY, INC., 0F NORTH CHICAGO, ILLINOIS, A CORPORATION OF NEI/V YORK.

NONAQUEOUS ELECTROLYTIC CONDENSER.

Application filed August 2.9, 1927. serial No. 216,122.

p This invention relates to electrolytic con- 'denlsers" of' the type using electrodes 'of filmed metal 'such asqaluminum, tantalum, etc., in a suitable electrolyte solution.

Electrolytic 'condensers utilize as a dielectric the resistant film formed on an aluminum platef- This fil-m isoften broken down:

Aor dissolved bythe electrolytesolution when the i condenser`= stands idle and it is often broken' down by excessive loads. It is also vsubject .to leakage due tov imperfections in 'formingor impurities in the aluminum.

"ThembJY-fct 'of this'invention isI to overcome these' "tlifficulties-I A.y further -object is to. provide f an electrolyti lcondenser in` which the'tilm ispermanent, even over periods of idleness.

A further object is to provide an electrolyte solution which will not evaporate.

A further object is to provide an electrolyte solution which will not creep.

A further object is to provide an electrolyte solution which will permit gas to escape under over load conditions and which will be more self-healing than electrolyte solutions now used; that is, which Will cause the film to re-form more readily after it has been broken down.

A further object is to provide an electrolyte condenser in which leakage current is reduced to a minimum, in which internal resistance is very low, and which is practically permanent.

Other objects will be apparent as the details of the. description proceed.

Preferred embodiments of my invention are disclosed in the acconxpanying (.lrt-uvngs, in which Fig. 1 represents diagrammatic-ally a simple condenser using two aluminum electrodes; and

Fig. 2 represents a unidirectional condenser having an iron electrode and a plurality of aluminum electrodes.

A suitable receptacle l0 of glass or any other material not affected by a glycerin s0- lution contains an electrolyte solution 1l which is prepared by dissolving one ounce of sodium bicarbonate in a liter of polyhydrio alcohol such as ethylene glycol or a commercial glycerin (glycerol). vWhile sodium bicarbonate has been found to give excellent results, it is understood that any acid, base or salt-that is, any ionogen-can be used in its place. Sodium bi-carbonate, however,

is preferred because it has been found to y1eld a more uniform and a more permanent fihn. Likewise I desire it to be understood that although I prefer to employ a polyhydric alcohol such as glycerin` other polyhydric alcohols and monohydrie alcohols such as butyl. alcohol may be employed, and my invention includes all such equivalent elements.

Filmed electrodes 12 and 13 are immersed in the glycerin solution and are connect-ed to an electrical circuit by conductors 1st and l5. A layerl of oil 16. is preferably maintained above the surface of the glycerin solution in order to prevent the evaporation of glycerin or the absorption of wat-er from the atmosphere.

The filmed plates are preferably prepared by thoroughly cleaning them in sodium carbonate and acid solutions to remove organic and inorganic impurities, subjecting them to an A. C. potential of about 325 volts in a dilute aqueous solution, subsequently subjecting them to a D. C. potential of about 280 volts in the same solution and finally subjecting them to a D. C. potential of about 250 volts in the substantially dry glycerin solution. A

The forming process per se may be accomplished in any conventional manner.

Fig. 2 represents diagrammatically a ty pc of electrolytic cont'lcnser which has been found very satisfactory t'or radio power units.

A suitable receltacle ltl contains :i glyc erin solution ll' into which :lr-c imincrslwl :a plurality olI filmed plates or j froups oi' 1latcs 17. These form the positivilcrminal of the condenser, the films form the dielectric and the glycerin solution acts as the negative plate. It is desirable., however, to introduce an'iron electrode 1S to serre as a conductor for dcscreasing the internal re. Vance of the cell and conducting the electricity to Ya ions parts of the electrolyte solution.

The use of glycerin instead of water for dissolving the electrolyte offers many marked and unexpected advantages. The film is maintained practically permanent, even during periods of idleness, and is easily reformed when broken down by overload currents. The electrolyte solution does not creep or evaporate and has been found to give excellent results in commercial applications.

The' term ioiiloyg'ezn as used in the' Clms is a generic expression which includes acids, bases, salts and/or .other substances which ionize and c'ciiidliclfa crrent .in certain solutions and/0r in fluid conditions. An electrolyte is, therefore, an muggen-solution. A

The expression substantially dry, as used in the appended claims, :does notinean that no trace of water is present but that the electrolyte 'is 'essentially la solution 4of the ion'ogen in gylceriii as distinguished fr'om an aqueous solution to which glyoel'i has been added. 't A A While I have describe `l a particular feinbodinient et my invention; t it.' is understmod that. I am not. llii'n'ited 'to lthe details shown except, its deinei'lby the following@claims:-

I claim: l Y

1. 'In eiect'rl'ytic ppa'vatus, filmed electrode enda-n ionogendissolved ih glycerin. 2. A n 'electrolybic condenser including a '-iled lelectr()de immers-'ed in a'sollliton o 1an iono'gen dissolved insubstantiaily dryglycerin.

In combination,i1-contarme; a substantially dry solution of an ionogen '1n glycerin,

lglycerin selution lined luni'ininr electrode' imiiersed in said solution, a second electrode in electrical contact with seid solution, and a seal above said solution to prevent the absorption f water.

4. A condenser comp'risinkg'a 'ire'd aluminnm electrode, an electrode of non-filming metal, an iono'gen 'dissolved in glycerin, and an oil layer above said glycerin to prevent evaporation and Water absorption.

5. .A condenser comprising a plurality of filmed electrodes, a conductive electrode, and an ionogen dissolved .in ,sub'stantially dry glycerin,` Whe1eb-y-the filmed electrode acts as ene-plate, the ilmxas a .dialectric and "the as the other plate, "the conductive-electrode merely serving to distribute the current through' bheg'lycenin. 'Y

6. 1:0 -eleotrol'ytic apparatus, a filmed elec- Jorocl'e and an .'io-nogen dissolved in a 'substantially dry galcohol.

7-, In electrolytic apparatus, affilmed electrode and au onogendissolved in s. sbstvantially dry polyhydric alcohol.

In Witness-whereof, Ihereunb'o subscribe 'my name this 23rd day ofAngus@ 1927 EDGAR W. NGLE, 

